Laminated composite materials, in which reinforcing fibres are held within a polymeric matrix, are extensively used in many engineering applications. Such materials can generally provide a higher strength and stiffness per unit weight than conventional metallic materials. This makes such composite materials advantageous for weight sensitive applications, such as those in the field of aerospace.
Conventional methods for manufacturing components from composite materials typically require extensive tooling fixtures and labour-intensive assembly procedures.
It is well known to automate the placement of composite fibres and/or tows for rapid, cost effective, net shape composite part manufacture. Such automated fibre placement methods can efficiently and reliably produce composite components using rotationally symmetrical, and/or contoured surface moulds.
A typical automated fibre tow placement machine comprises a tow dispensing head which moves across the surface of the mould and which is followed by a mechanical consolidation device such as a wheel or roller. In this context, the term consolidation is used to refer to the process of pressing the tows together to form a shaped article having a low level of internal voids. The shaped article may then be cured to form the finished component.
However, a known problem with such automated tow placement techniques is encountered when the surface geometry of the mould includes complex curvatures. In such moulds it can be difficult to ensure that the consolidation device follows the contours of the mould when consolidating the applied tows.
This can lead to the tows not being properly consolidated against the mould surface with the result that voids are generated within the shaped article. In extreme cases it may lead to the tows not following the surface of the mould, for example by ‘bridging’ recesses in the mould, which results in an incorrectly shaped article which must then be scrapped.